The Wisconsin Supreme Court upheld a requirement Thursday that voters show photo identification at the polls, but the law remains blocked in federal court.

MADISON, Wis. — The Wisconsin Supreme Court upheld a requirement Thursday that voters show photo identification at the polls, but the law remains blocked in federal court.

For the state law to take effect, the 7th U.S. Circuit Court of Appeals would have to overturn a federal judge's decision in April that struck it down as unconstitutional.

Wisconsin's Republican-led Legislature passed the photo ID requirement and Gov. Scott Walker signed it in 2011, achieving a long-sought GOP priority. Former Gov. Jim Doyle, a Democrat, had vetoed a similar requirement three times between 2002 and 2005.

Republican backers argued an ID requirement would cut down on voter fraud and boost public confidence in the integrity of the election process. But opponents say concerns over voter fraud were overblown and not documented, and the law was meant to reduce turnout among minorities and others likely to vote for Democrats.

Walker said in a statement Wednesday: "Voter ID is a common sense reform that protects the integrity of our elections ... We look forward to the same result from the federal court of appeals."

U.S. District Judge Lynn Adelman, in striking down the law in April, said the state was unable to prove its case and the law violated the U.S. Constitution's guarantee of equal protection. The U.S. Justice Department sided Wednesday with challengers in the federal court case, saying that the photo ID requirement unfairly affected minority voters; the department also took a similar stand on an Ohio law that limits when voters can cast an early ballot.

Thirty-four states have passed laws requiring some sort of identification from voters, but only 31 of them are in effect, according to the National Conference of State Legislatures. Like in Wisconsin, a court has struck down Pennsylvania's law, and one passed in North Carolina won't take effect until 2016.

The state Supreme Court issued rulings in two cases Thursday, concluding in both that the law was constitutional. One was brought by the League of Women Voters and the other came from the Milwaukee branch of the National Association for the Advancement of Colored People and immigrant rights group Voces de la Frontera.

In the NAACP case, the Supreme Court said the state can't require people to pay fees to receive state-issued ID cards. Doing so would be a "severe burden on the constitutional right to vote," Justice Pat Roggensack wrote.

Currently, it costs $20 each to obtain copies of a birth certificate, which is needed to obtain an ID card if a person doesn't have another acceptable form of identification. The court interpreted the state's administrative code to mean that the Division of Motor Vehicles cannot require someone to present any documents that cost money in order to get a voter ID.

The court ruled 4-3 in favor of the law in the NAACP case and 5-2 in the League of Women Voters lawsuit.

Chief Justice Shirley Abrahamson wrote a blistering dissent, arguing that the law is unconstitutional.

"Today the court follows not James Madison — for whom Wisconsin's capital city is named — but rather Jim Crow — the name typically used to refer to repressive laws used to restrict rights, including the right to vote, of African-Americans," Abrahamson wrote.